In the aforementioned parent application, a contact lens for light sensitive lens wearers is shown having a progressively optically graded area therein. Such a lens has been found to be useful in screening the light entering the pupil of the eye of the light sensitive wearer, wherein the amount of light falling upon the retina is automatically adjusted.
The gradation in optical density of the lens extends across the lens from a relatively darker central portion to a relatively lighter peripheral portion.
The present invention, among other things, teaches a simple but effective method for fabricating graded light occluding gels generally, using the technique of electrophoresis. An ionized dye is brought into contact with the lens gel material at a central point. An electric potential is applied across the lens gel, causing the dye to migrate from its source, towards the periphery of the lens. Through control of ionic concentrations, and the geometry of the applicator system, this can cause a graded concentration of dye to be disbursed across the lens, i.e., there is a higher concentration of dye at the central point, which concentration progressively diminishes as the distance from the central point.